Negative online product reviews generated by current users can influence potential adopters' new product evaluation and set up diffusion barriers. Integrating the social functions of emotion theory with the innovation diffusion context, this research proposes that the emotional intensity expressed in angry online reviews influences potential adopters' new product evaluation through two competitive routes (i.e., in an opposite direction): perceived problem seriousness in the review and perceived rationality of the reviewer, thus establishing two simultaneous mediations in the conceptual framework. Furthermore, this research suggests that the two mediations are moderated by product innovativeness. This investigation was completed in three experiments with consumers recruited via Amazon Mechanical Turk (MTurk). Study 1 manipulated anger intensity in two levels expressed in a single negative review, using a smartphone as the reviewed new product. Study 2 employed a multi‐review setting, including negative, neutral, and positive reviews, using an E‐reader as the reviewed new product. The multi‐review setting was also adopted in Study 3, where three levels of anger were manipulated. Three studies adopted an incrementally versus really new product version to manipulate innovativeness. Combined findings of the three studies support the proposed dual mediation processes. In addition, results show that the mediation effect of problem seriousness in the review is stronger for a really new product than an incrementally new product. This research extends the underpinning of innovation diffusion literature and provides managerial implications for new product launch management. First, it identifies that anger intensity expressed in a new product review socially influences a potential adopter's concurrent appraisals of the reviewed product and the reviewer. The two appraisal routes mediate the impact of anger intensity on new product evaluation in opposite directions. Second, the research explores and identifies which mediation route is more influential on new product evaluation when product innovativeness varies.